Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757244AbbDVSUr (ORCPT ); Wed, 22 Apr 2015 14:20:47 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:33020 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753143AbbDVSUq (ORCPT ); Wed, 22 Apr 2015 14:20:46 -0400 MIME-Version: 1.0 In-Reply-To: <5537E1D9.6010609@hp.com> References: <20150418013256.25237.96403.stgit@dwillia2-desk3.amr.corp.intel.com> <20150418013535.25237.4770.stgit@dwillia2-desk3.amr.corp.intel.com> <1429644912.17259.31.camel@misato.fc.hp.com> <1429646156.17259.39.camel@misato.fc.hp.com> <1429720742.15952.30.camel@misato.fc.hp.com> <5537E1D9.6010609@hp.com> Date: Wed, 22 Apr 2015 11:20:44 -0700 Message-ID: Subject: Re: [Linux-nvdimm] [PATCH 04/21] nd: create an 'nd_bus' from an 'nfit_desc' From: Dan Williams To: Linda Knippers Cc: Toshi Kani , "linux-kernel@vger.kernel.org" , "linux-nvdimm@lists.01.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4647 Lines: 95 On Wed, Apr 22, 2015 at 11:00 AM, Linda Knippers wrote: > On 4/22/2015 1:03 PM, Dan Williams wrote: >> On Wed, Apr 22, 2015 at 9:39 AM, Toshi Kani wrote: >>> On Tue, 2015-04-21 at 13:35 -0700, Dan Williams wrote: >>>> On Tue, Apr 21, 2015 at 12:55 PM, Toshi Kani wrote: >>>>> On Tue, 2015-04-21 at 12:58 -0700, Dan Williams wrote: >>>>>> On Tue, Apr 21, 2015 at 12:35 PM, Toshi Kani wrote: >>>>>>> On Fri, 2015-04-17 at 21:35 -0400, Dan Williams wrote: >>>>>>> : >>>>>>>> + >>>>>>>> +static int nd_mem_init(struct nd_bus *nd_bus) >>>>>>>> +{ >>>>>>>> + struct nd_spa *nd_spa; >>>>>>>> + >>>>>>>> + /* >>>>>>>> + * For each SPA-DCR address range find its corresponding >>>>>>>> + * MEMDEV(s). From each MEMDEV find the corresponding DCR. >>>>>>>> + * Then, try to find a SPA-BDW and a corresponding BDW that >>>>>>>> + * references the DCR. Throw it all into an nd_mem object. >>>>>>>> + * Note, that BDWs are optional. >>>>>>>> + */ >>>>>>>> + list_for_each_entry(nd_spa, &nd_bus->spas, list) { >>>>>>>> + u16 spa_index = readw(&nd_spa->nfit_spa->spa_index); >>>>>>>> + int type = nfit_spa_type(nd_spa->nfit_spa); >>>>>>>> + struct nd_mem *nd_mem, *found; >>>>>>>> + struct nd_memdev *nd_memdev; >>>>>>>> + u16 dcr_index; >>>>>>>> + >>>>>>>> + if (type != NFIT_SPA_DCR) >>>>>>>> + continue; >>>>>>> >>>>>>> This function requires NFIT_SPA_DCR, SPA Range Structure with NVDIMM >>>>>>> Control Region GUID, for initializing an nd_mem object. However, >>>>>>> battery-backed DIMMs do not have such control region SPA. IIUC, the >>>>>>> NFIT spec does not require NFIT_SPA_DCR. >>>>>>> >>>>>>> Can you change this function to work with NFIT_SPA_PM as well? >>>>>> >>>>>> NFIT_SPA_PM ranges are handled separately from nd_mem_init(). See >>>>>> nd_region_create() in patch 10. >>>>> >>>>> If nd_mem_init() does not initialize nd_mem objects, nd_bus_probe() in >>>>> core.c fails in nd_bus_init_interleave_sets() and skips all subsequent >>>>> nd_bus_xxx() calls. So, nd_region_create() won't be called. >>>>> >>>>> nd_bus_init_interleave_sets() fails because init_interleave_set() >>>>> returns -ENODEV if (!nd_mem). >>>> >>>> Ah, ok your test case is specifying PMEM backed by memory device >>>> info. We have a test case for simple ranges (nfit_test1_setup()), but >>>> it doesn't hit this bug because it does not specify any memory-device >>>> tables. >>> >>> Yes, we have NFIT table with SPA range (PM), memory device to SPA, and >>> NVDIMM control region structures. With the memory device to SPA >>> structure, this code requires full sets of information, including the >>> namespace label data in _DSM [1], which is outside of ACPI 6.0 and is >>> optional. Battery-backed DIMMs do not have such label data. >> >> This is what "nd_namespace_io" devices are for, they do not require labels. >> >> Question, if you don't have labels and you don't have DSMs then why >> publish a MEMDEV table at all? Why not simply publish an anonymous >> range? See nfit_test1_setup(). > > The MEMDEV table provides useful information, and there may be _DSMs, > perhaps just not the same _DSM as some other devices. > >>> It needs >>> to work with NFIT table with these structures without this _DSM or with >>> a different type of _DSM which this code may or may not need to support. >>> It should also check Region Format Interface Code (RFIC) in the NVDIMM >>> control region structure before assuming this _DSM is present to >>> implement RFIC 0x0201. >> >> Ok I can look into adding this check, but I don't think it is >> necessary if you simply refrain from publishing a MEMDEV entry. > > But we need the MEMDEV. And as Toshi mentions, we could have other > RFICs with other _DSMs than your example. That's why there is an RFIC. Wait, point of clarification, DCRs (dimm-control-regions) have RFICs, not MEMDEVs (memory-device-to-spa-mapping). Toshi's original report was that an NFIT with a SPA+MEMDEV was failing to enable a PMEM device. That specific problem can be fixed by either deleting the MEMDEV, or adding a DCR. Of course, if you add a DCR with a different intended DSM layout than the DSM-example-interface the driver will need to add support for handling that case. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/